Method of reducing fumes from a vessel of molten asphalt

ABSTRACT

A method and container for reducing fuming of asphalt in a heated vessel, including placing asphalt in a heated vessel to heat the asphalt to a molten state, adding a blanket material to the asphalt, the blanket material being substantially insoluble in the molten asphalt to form a skim thereon to reduce fuming therefrom.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part of copending Ser. No.09/169,964 to Marzari et al., filed Oct. 13, 1998.

TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE INVENTION

[0002] This invention relates in general to asphalt materials for use inroofing, paving and other applications. More particularly, thisinvention relates to a container and method to produce such a container,for reducing fumes emitted from a vessel of the molten asphalt. Theinvention can be useful for providing asphalt for use in locations wherefumes from the molten asphalt are a concern.

BACKGROUND OF THE INVENTION

[0003] Asphalt from processing and terminalling facilities istransported to end users in one of several ways, including direct pipingof molten asphalt to nearby customers, shipping in molten form viatanker truck, railcar and barge, and shipping in solid form inindividual packages. The packages are used primarily by buildingcontractors as a source of asphalt for roofing applications. Thecontractor typically places the solid asphalt in a heated kettle to meltthe asphalt for use. Asphalt shipped in molten form is also usuallyfurther heated in a kettle prior to use.

[0004] A problem associated with such heated kettles of molten asphaltis that they can emit significant amounts of fumes. The fumes can beunsightly, and an irritant to workers and others in the surroundingarea. Accordingly, it would be desirable to reduce the amount of fumesnormally emitted from a kettle or other vessel of molten asphalt.

[0005] It would also be desirable to reduce fuming and odors withoutsubstantial modification of the processed or raw asphalt. By contrastwith known polymer-modified asphalt compositions, which are highlymodified materials where the polymer is used, e.g., to impart elongationproperties, an asphalt without such modification is desired for manyapplications.

[0006] It would also be desirable to reduce fuming and odors of moltenasphalt while permitting for convenient, user-tailorable enhancement oralteration of the asphalt properties.

[0007] Furthermore, it would be desirable to produce a low-fumingasphalt in a convenient package. Individual packages of asphalt aretypically formed at conventional asphalt processing facilities bypouring molten asphalt into containers made of a metal bottom and papercylindrical sidewalls. The asphalt is typically poured at temperaturesof about 177° C. and the packages are allowed to cool for up to 24 hoursprior to shipping.

SUMMARY OF THE INVENTION

[0008] The above objects as well as other objects not specificallyenumerated are achieved by adding a blanket material to a kettle ofmolten asphalt to form a skim layer.

[0009] In a preferred embodiment, a method for reducing fuming ofasphalt in a heated vessel includes placing asphalt in a heated vesselto heat the asphalt to a molten state. A blanket material is added tothe asphalt, the blanket material being substantially insoluble in themolten asphalt to form a skim thereon to reduce fuming therefrom.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 is a schematic representation of a package of asphalt.

[0011]FIG. 2 is a schematic view in perspective of a kettle for meltingasphalt.

DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS OF THE INVENTION

[0012] Advantageously, it has been found that the addition of a blanketmaterial to a vessel of asphalt helps to reduce fumes emitted from avessel of the molten asphalt. The term “vessel” means any kettle,container or other receptacle suitable for holding molten asphalt, suchas a roofer's kettle, an asphalt package, a bulk storage tank, a tankertruck, a railcar or a barge. While the asphalt is being held in thevessel, it may be held for heating, storing, transporting or dispensing.

[0013] The inventors have found that it is most convenient for the enduser of the asphalt to have the blanket material contained in theasphalt package. Alternatively, the blanket material may be added at thejobsite. The blanket material is intended to form a skim layer on top ofthe molten asphalt to reduce fuming. The term “skim” means a layer,film, or coating which floats, forms, or collects on the upper surfaceof the molten asphalt. Preferably, the blanket material forms a skimacross at least about 80-90% of the upper surface of the molten asphalt,and more preferably across substantially the entire upper surface of themolten asphalt. It is understood that when additional asphalt is placedinto the vessel, the skim may be broken but it usually quickly re-formsover the surface.

[0014] While not intending to be limited by theory, it is believed thatthe skim reduces fuming from the vessel by acting as a cool top orbarrier to exposure of the molten asphalt to air. The thickness of theskim is a function of the addition rate of blanket material minus theblanket material's combined removal and dissolution rate. Thedissolution rate is a function of fundamental blanket materialproperties as well as vessel temperature and agitation level. Theremoval rate is a function of how the asphalt is removed form the vesselas well as the effect of the vessel temperature on the blanket material.The thickness of the skim is usually from about 3 mm to about 50 mm, andtypically about 13 mm, but varies greatly with the blanket materialused. However, it is believed that a skim thickness of at least about0.025 mm, more preferably greater, is suitable for reducing fuming fromthe vessel.

[0015] The inclusion of blanket materials to form such skims mayadvantageously be used with any asphalt product that is generally heatedin an open kettle in preparation for its use. As used herein the term“asphalt” is meant to include asphalt bottoms from petroleum refineries,as well as naturally occurring bituminous materials such as asphalts,gilsonite, tars, and pitches, or these same materials that have beenair-blown or otherwise chemically processed or treated. For example, theasphalt can be air-blown with catalysts such as ferric chloride and thelike. The asphalt can be a conventional roofing flux asphalt or apaving-grade asphalt, as well as other types of asphalts, includingspecialty asphalts such as water-proofing asphalts, battery compounds,and sealers. Blends of different kinds of asphalt can also be used.

[0016] The blanket material added to the asphalt can be any blanketmaterial substantially incapable of melting and/or substantiallydissolving in the asphalt, and forming a skim of sufficient viscosity onthe upper surface of the molten asphalt to reduce fuming from thekettle. The blanket material should have a relative density lower thanthat of the asphalt so that it rises to the upper surface of a kettle ofthe molten asphalt. These properties should exist for at least thenormal termperatures at which asphalt is heated during application.Typical temperatures are approximately 200 degrees C. to an uppertemperature of about 275 degrees C., but it is preferable that suchproperties exist even if the asphalt is heated outside this temperaturerange.

[0017] Exemplary blanket materials that may be used include inertblanket materials, such as polyurethane, PET, such as ground sodabottles, Starch (such as from packaging materials), cellulose materials,such as newsprint, sawdust, wood chips, and such.

[0018] The skim is preferably viscous enough so that it stays togetheras a continuous layer to reduce fuming from the vessel, or thick enoughto act as a blanket on top of the molten asphalt. If the viscosity ofthe skim is too low, or the blanket too thin, fumes from the moltenasphalt could break up through holes in the skim and escape from thevessel. In contrast, if the viscosity is too high, the blanket materialwill not easily form a continuous skim over the entire exposed surfaceof the asphalt, nor redisperse or dissolve easily into the bulk asphaltover time.

[0019] Although a wide range of blanket materials are useful in theinvention, as suggested from the list above, the blanket materialselected for use with a particular asphalt should not undesirably modifythe properties of the asphalt in the amount added, nor undulycontaminate the molten asphalt. For example, where the asphalt isintended to be used as a roofing asphalt, it is preferred that both theasphalt without (before addition of) the blanket material, and with theblanket material, meets the requirements for at least one type ofroofing asphalt according to ASTM D312, more particularly ASTM D312-89.Accordingly, it is preferred that the addition of the blanket materialto the asphalt reduces fuming but does not significantly change theproperties of the asphalt. More preferably, the asphalt with the addedblanket material meets the following ASTM D312 specifications for a TypeIII roofing asphalt: softening point (by ASTM D36) of 85-96° C.; flashpoint of 246° C. minimum; penetration (by ASTM D5) at 0° C. of 6 dmmminimum, at 25° C. of 15-35 dmm, and at 46° C. of 90 dmm maximum;ductility (by ASTM D-113) at 25° C. of 2.5 cm minimum; and solubility(by ASTM D2042) in trichloroethylene of at least 99%. Preferably theaddition of the blanket material to the asphalt does not change thesoftening point of the asphalt by more than about 9° C., more preferablynot more than about 3° C., and does not change the penetration of theasphalt by more than about 10 dmm at 25° C. More preferably, the blanketmaterial substantially forms a blanket that floats on the top of themolten asphalt, and does not mix with the asphalt and therefore has nosignificant effect on the asphalt properties whatsoever. Even morepreferably, the blanket absorbs some of the fumes.

[0020] The blanket material is typically added to the asphalt in anamount sufficient to reduce the visual opacity of the fumes from thevessel by at least about 25% with respect to the same asphalt withoutthe blanket material. The visual opacity of the to fumes is a measure ofthe blockage of natural light by the fumes. The more fumes emitted fromthe vessel, the higher the visual opacity. Conversely, a reduction inthe visual opacity indicates a reduction in the amount of fumes emittedfrom the vessel. Preferably, the blanket material is added in an amountsufficient to reduce the visual opacity of the fumes by at least about35%, more preferably at least about 50-60%, and even more preferably atleast about 70-80%.

[0021] The reduction in visual opacity of the fumes increases at highertemperatures where fuming is at its worst with conventional asphaltproducts. Kettles of roofing asphalt are typically heated totemperatures of from about 232° C. to about 288° C. Preferably the addedblanket material reduces the visual opacity of the fumes by at leastabout 35% at 260° C., and more preferably at least about 50% at 260° C.

[0022] Further, the total emissions of benzene soluble suspendedparticulates from the vessel is typically reduced by at least about 15%over the same asphalt without the blanket material. Preferably the totalis reduced by at least about 25%, more preferably at least about 40-50%,and even more preferably at least about 60-70%. The total benzenesoluble suspended particulate emissions is made up of the smallparticles of benzene soluble solid materials present in the fumes, sothat a reduction in such particulate emissions indicates a reduction inthe amount of fumes emitted. Preferably the total suspended particulatesemissions is reduced by at least about 25% at 260° C., and morepreferably at least about 50% at 260° C.

[0023] To provide a skim to achieve such reductions in fuming, theconcentration of blanket material is preferably sufficient to form askim over the entire exposed surface of the asphalt in the vessel.Preferably, the amount of blanket material added is within the range offrom about 0.2% to about 6% by weight based on the total weight of theasphalt and blanket material. More preferably, from about 0.2% to about2%, and even more preferably, from about 0.3% to about 0.5% blanketmaterial is added based on the total weight of asphalt and blanketmaterial. At such levels, the amount of fumes normally emitted from avessel of the molten asphalt is significantly reduced without anysignificant modification of the asphalt properties.

[0024] As noted above, the blanket materials may be ground up and placedin a container of asphalt when the asphalt is formed into kegs. Theblanket material may be placed on the bottom of an asphalt container andthe asphalt poured onto the blanket material, or the blanket materialmay be added in the middle or top of the container. Alternatively, theblanket material may be added at the jobsite by adding the blanketmaterial to the vessel of molten asphalt. One jobsite method includesshredding the paper from the shipping carton for the asphalt and puttingthe shredded paper into the vessel. Alternatives include having bags ofblanket material at the jobsite which are added periodically to thevessel as needed. Furthermore, the present invention may be used incombination with the polymers described in commonly assigned U.S. Pat.No. 6,130,276, which is incorporated herein by reference in itsentirety, or in combination with a consumable container, or with asphaltshipped in a plastic or paper wrapper or bag.

[0025] Referring now to a preferred embodiment of a consumable containerfor asphalt shown in the drawings, there is illustrated in FIG. 1 anasphalt package 10, including a container 11, typically havingcylindrical sides 12 made of paper or cardboard, and a steel bottom 14pressed thereon. At a jobsite, the paper 12 and bottom 14 are removedand discarded, and the asphalt 14 is thrown into a kettle.

[0026]FIG. 2 illustrates a vessel 20 for melting asphalt 28. The vessel20 has walls 22 for holding the asphalt 28 and a source of heat 30 forheating the vessel to melt the asphalt 28. A blanket material 24 isadded to the vessel 20 and forms a blanket layer 26 on top of theasphalt 28.

[0027] The invention will now be further illustrated by reference to thefollowing examples.

EXAMPLE 1

[0028] Testing was conducted to measure the ability of a minor amount ofblanket material added to a vessel melting a conventionally packagedasphalt product to reduce fuming from a kettle of the molten asphaltduring remelting. In this test, fuming of a standard BURA Type IIIasphalt (Amoco roofer's flux asphalt air-blown to a softening point offrom about 85° C. (185° F.) to about 96.1° C. (205° F.)), packaged in aconventional paper container, was tested both with an amount of blanketmaterial added to the kettle (“low-fuming product”), and without theadded blanket material (“standard product”).

[0029] The blanket material added to the low-fuming product was preparedby cutting standard newsprint into small pieces (about 1 mm square).

[0030] A gallon of type III asphalt was heated by a propane burner to260° C. (500° F.) and the shredded newsprint was added and the mixtureagitated. Approximately 8 g of newsprint was added to 2.27 Kg. (5 lb.)of asphalt (0.4%) and the temperature was measured at 207° C. (405° F.).Small bubbles formed and the newsprint swelled to 2.55.0 cm. (1-2inches) thick and the fumes coming off the asphalt were significantlyreduced (approximately 90%).

EXAMPLE 2

[0031] The testing of Example 1 was repeated, but in Example 2, thenewsprint was dried prior to adding to the vessel. The newsprint did notswell as thickly as in Example 1 and fuming was reduced to a slightlylesser magnitude.

EXAMPLE 3

[0032] The test of Example 1 was repeated, using sawdust in place of thenewsprint. 2 gr. (0.088%) of sawdust was added to the asphalt and alayer was formed on top of the molten asphalt that swelled to about 2.5cm. (1 inch) thick, and the fuming was reduced. As an additional 2 gr.Sawdust was added, the fuming was further reduced.

EXAMPLE 4

[0033] 454 grams (1 lb.) of Type III asphalt was heated and 1.6 g. ofpolyurethane was added (CELOTEX® board was ground into small particles),the polyurethane was not miscible, and where it covered the asphalt,fumes were reduced. It is expected that by adding enough polyurethane, amore complete layer would be formed and fuming further reduced.

EXAMPLE 5

[0034] 2.5 g of PET (from ground soda bottles) was added to 454 grams (1lb.) of Type III asphalt. The PET did not melt until about 250° C. (480°F.), and the unmelted PET reduced fuming to a small extent where a skimlayer was formed.

EXAMPLE 6

[0035] 2 grams of PET fibers (Hoescht Celanese L3 1010) was added to 454grams (1 lb.) of Type II asphalt. Fuming was visibly reduced at 265° C.(510° F.).

EXAMPLE 7

[0036] 2 g. of starch was made from broken down packaging bubbles andadded to to 454 grams (1 lb.) of Type II asphalt. Fuming was reduced byabout 60% at 270° C. (520° F.).

[0037] The blanket material may be added to the asphalt prior to, orduring pouring into a container at the asphalt manufacture facility.Alternatively, such blanket materials may be added at the jobsite.

[0038] Breakage means, such as decried in my copending application Ser.No. 09/169,964 may be inserted inside the container adjacent the wallsto provide a breakage means or other feature in the asphalt container.Such breakage means may be inserted as a rod or bar adjacent thesidewall, in place of the string illustrated in the figures, and therebyprovide a means for tearing the sidewall. The same breakage meansprovides an indentation in the asphalt block and therefore facilitatesbreakage of the block, while also providing a further source of polymerin the kettle.

[0039] In a further alternative embodiment, a polymer material is addedto the kettle in addition to the blanket material described herein. Suchpolymer material is described in commonly assigned U.S. Pat. Nos.6,130,276, 6,107,373, 6,069,194 5,992,628 5,989,662 and 5,733,616, whichare incorporated herein by reference. The polymers of these applicationstypically melt while the asphalt is heated and dissolve within themolten asphalt over time. The present invention, however, uses a blanketmaterial which is substantially insoluble and/or not dissolved in theasphalt.

[0040] Although the invention has been described in detail in referenceto preferred feature and embodiments, appropriate modifications will beapparent to the artisan. Thus, the invention is intended not to belimited by the foregoing description, but to be defined by the appendedclaims and their equivalents.

What is claimed is:
 1. A method for reducing fuming of asphalt in aheated vessel, comprising placing asphalt in a heated vessel to heat theasphalt to a molten state; adding a blanket material to the asphalt, theblanket material being substantially insoluble in the molten asphalt toform a skim thereon to reduce fuming therefrom.
 2. A method according toclaim 1, wherein the blanket material remains substantially unmeltedwhen heated to a temperature of 275 degrees C.
 3. A method according toclaim 1, wherein the blanket material comprises a thermoset material. 4.A method according to claim 3, wherein the blanket material comprises acellulose material.
 5. A method according to claim 4, wherein theblanket material comprises newsprint.
 6. A method according to claim 4,wherein the blanket material comprises sawdust.
 7. A method according toclaim 4, wherein the blanket material comprises asphalt packagingmaterial.
 8. A method according to claim 1, wherein the blanket materialcomprises a PET material.
 9. A method according to claim 1, wherein theblanket material comprises a starch material.
 10. A method according toclaim 1, wherein the asphalt and blanket material are placed into avessel and heated to melt the asphalt, the molten asphalt normallyemitting fumes from the vessel, and the blanket material forms a layeron top of the asphalt when the asphalt is melted in the vessel to reducethe visual opacity of the fumes by at least about 25% with respect tothe same asphalt without the blanket material.
 11. A method according toclaim 10, wherein the skim layer expands to at least 13 mm thick. 12.The method of claim 10, wherein the amount of the blanket material issufficient to reduce the hydrocarbon emissions of the fumes by at leastabout 10% of the hydrocarbon emissions from the melted asphalt in theabsence of the blanket material.
 13. The method of 10, wherein theamount of the blanket material is sufficient to reduce the totalsuspended particulates emissions of the fumes by at least about 10% ofthe total suspended particulates emissions from the melted asphalt inthe absence of the blanket material.
 14. A method according to claim 1,wherein the asphalt is solidified prior to being placed into the heatedvessel and the blanket material is added to the asphalt after theasphalt is solidified.
 15. A method according to claim 14, wherein theblanket material is added to the asphalt in the heated vessel.
 16. Amethod according to claim 1, wherein the asphalt is solidified prior tobeing placed into the heated vessel and the blanket material is added tothe asphalt prior to the asphalt being solidified.
 17. A container oflow fuming asphalt, comprising: a package for holding asphalt; asphaltsolidified in the container; a blanket material provided in the asphaltcontainer with the asphalt, the blanket material being substantiallyinsoluble in the molten asphalt to form a skim on top of the asphaltwhen the asphalt is in a molten state within a heated vessel.
 18. Acontainer according to claim 17, wherein the blanket material comprisesa thermoset material.
 19. A container according to claim 18, wherein theblanket material comprises a cellulose material.
 20. A containeraccording to claim 19, wherein the blanket material comprises newsprint.21. A container according to claim 19, wherein the blanket materialcomprises sawdust.
 22. A container according to claim 19, wherein theblanket material comprises asphalt packaging material.
 23. A containeraccording to claim 17, wherein the blanket material comprises a PETmaterial.
 24. A container according to claim 17, wherein the asphalt andblanket material are placed into a vessel and heated to melt theasphalt, the molten asphalt normally emitting fumes from the vessel, andthe blanket material forms a layer on top of the asphalt when theasphalt is melted in the vessel to reduce the visual opacity of thefumes by at least about 10% with respect to the same asphalt without theblanket material.
 25. A container according to claim 17, wherein theasphalt and blanket material are placed into a vessel and heated to meltthe asphalt and bottom, the molten asphalt normally emitting fumes fromthe vessel, and the blanket material forms a layer on top of the asphaltwhen the asphalt is melted in the vessel to reduce the visual opacity ofthe fumes by at least about 25% with respect to the same asphalt withoutthe blanket material.
 26. A container according to claim 25, wherein theskim layer expands to at least 13 mm thick.
 27. A container according toclaim 17, wherein the blanket material remains substantially unmeltedwhen heated to a temperature of 275 degrees C.
 28. A container of lowfuming asphalt, comprising: a package for holding asphalt; asphaltsolidified in the container; a blanket material provided in the asphaltcontainer with the asphalt, the blanket material being substantiallyundissolved in the molten asphalt to form a skim on top of the asphaltwhen the asphalt is in a molten state within a heated vessel.
 29. Acontainer according to claim 28, wherein the blanket material comprisesa thermoset material.
 30. A container according to claim 29, wherein theblanket material comprises a cellulose material.
 31. A containeraccording to claim 30, wherein the blanket material comprises newsprint.32. A container according to claim 30, wherein the blanket materialcomprises sawdust.
 33. A container according to claim 28, wherein theasphalt and blanket material are placed into a vessel and heated to meltthe asphalt, the molten asphalt normally emitting fumes from the vessel,and the blanket material forms a layer on top of the asphalt when theasphalt is melted in the vessel to reduce the visual opacity of thefumes by at least about 10% with respect to the same asphalt without theblanket material.
 34. A container according to claim 28, wherein theasphalt and blanket material are placed into a vessel and heated to meltthe asphalt and bottom, the molten asphalt normally emitting fumes fromthe vessel, and the blanket material forms a layer on top of the asphaltwhen the asphalt is melted in the vessel to reduce the visual opacity ofthe fumes by at least about 25% with respect to the same asphalt withoutthe blanket material.
 35. A container according to claim 28, wherein theskim layer expands to at least 13 mm thick.
 36. A container according toclaim 28, wherein the blanket material does not substantially melt whenheated to a temperature of 275 degrees C.
 37. A container according toclaim 28, wherein the blanket material is substantially insoluble in themelted asphalt.